THE BUCKLER PERNS. 47 



able interest on account of its rarity. It forms a thick 

 creeping stem or root-stock, from which a limited number of 

 narrow, very upright fronds arise early in May, and attain 

 the average height of j couple of feet. The fronds are 

 destroyed in autumn by the frosts. Their outline is linear- 

 oblong that is, from a narrow width at the base the mar- 

 gins run nearly parallel almost to the apex, where they 

 narrow to the point ; they are supported by a longish stipes, 

 which is proportionally stout, and maintains this propor 

 tion upwards through the leafy portion of the frond; on 

 the lower part it has a few scales, which are blunt ovate, 

 membranous, and of a uniform light brown colour. The 

 pinnse_are elongate-triangular in their outline, the broadest 

 occurring at the base of the frond, the upper ones becom- 

 ing gradually narrower, but all of the same general form, 



ZoitretL ariaiata. 



namely, widest at the base, gradually tapering to the apex. 

 They are not divided quite down to their midrib, so as to 

 become, in technical terms, pinnate, but each segment is at- 

 tached by the entire width of its base, and connected by a 

 narrow extension of its base with the segment next behind 

 it ; all the segments haying their apices inclined rather to- 

 wards the apex of the pinnae. The lobes of the pinnse are 

 themselves oblong, with a rounded apex, and a crenately 

 toothed margin. The midvein of the lobes takes a tortuous 

 course, and gives off lateral branches which divide into 

 several secondary branches, one only of which, that nearest 

 the apex of the lobe, bears a sorus. The fructification is 

 confined to the upper portion of the frond, and often re- 



